The Ford flathead V8 (often called simply the Ford flathead or flathead Ford when the V8 context is implicit, such as in hot-rodding) was a V8 engine of the flathead type, designed by the Ford Motor Company and built by Ford and various licensees. During the engine's first decade of production, when overhead valve engines were rare, it was usually known simply as the Ford V‑8, and the first car model in which it was installed, the Model 18, was (and still is) often called simply the "Ford V‑8", after its new engine. When the engine was introduced in 1932, it was a market first in several respects: in cars that were affordable to the emerging mass market consumer, it was the first 8-cylinder, the first V8, and the first V engine to become available. It was the first independently designed and built V8 engine produced by Ford for mass production, and it ranks as one of the company's most important developments. A fascination with ever-more-powerful engines was perhaps the most salient aspect of the American car and truck market for a half century, from 1923 until 1973. The Ford flathead V8 was perfectly in tune with the cultural moment of its introduction, leading the way into a future of which the Ford company was a principal architect. Thus it became a phenomenal success. The engine design, with various changes but no major ones, was installed in Ford passenger cars until 1953, making the engine's 21-year production run for the U.S. consumer market longer than the 19-year run of the Ford Model T engine for that market. The engine was on Ward's list of the 10 best engines of the 20th century. It was a staple of hot rodders in the 1950s, and it remains famous in the classic car hobbies even today, despite the huge variety of other popular V8s that followed.

The original flathead engine displaced 221 cu in (3.6 L), with 3.0625 by 3.75 in (77.79 by 95 mm) bore and stroke. The block was cast as a single piece (monobloc) for durability, and a single-barrel carburetor fed the engine. The 1932 V8-18 with 5.5:1 compression produced 65 hp. The 1933-34 V8-40 raised compression to 6.33:1and power to 75 hp (56 kW). In 1934 a two barrel down draft carburetor was introduced.^[1935's V8-48 saw compression drop to 6.3:1, but power climb to 85 hp (63 kW), and torque was rated at 144 lb·ft (195 N·m). It became the V8-68 in 1936, with compression, horsepower, and torque unchanged.

Production of the original 221 lasted from 1932 through to 1936. These engines can be identified by having the water pumps located at the front of the heads. A similar 221 flathead was used in Fords for 1937 and 1938 but the block was revised to have the water pumps mount to the block. The new design also relocated the water outlet from the front of the heads to the top center of the heads. These, designated V8-78, were offered with standard 6.2:1 compression aluminum or 7.5:1 compression iron cylinder heads, rated at 85 hp (63 kW) and 144 lb·ft (195 N·m) (aluminum) or 94 hp (70 kW) (iron). The 1932 through 1938 motors used twenty one studs to hold down each head and are known as "21 stud" motors.

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